This invention generally relates to a mounting fixture for holding fluid level sensors, and more particularly, to a mounting fixture for holding a variety of functionally different fluid sensors in a fluid measurement and control system.
In known chemical treatment systems, such as the one disclosed in U.S. Pat. No. 4,897,797 to Free, Jr. et al, a fluid such as water is treated with a treatment liquid as it flows through a conduit, and the treatment liquid is fed in controlled amounts by a proportional feed technique. The treatment liquid is stored in a storage tank and is pumped to the conduit by means of a pump which displaces a predetermined volume of liquid per each stroke. Thus, by determining the volume displaced by the pump during each stroke, the particular amount of treatment liquid fed to the conduit may be precisely controlled by controlling the number of strokes of the pump with regard to the flow rate of the liquid flowing through the conduit.
As is noted in U.S. Pat. No. 4,897,797, the displacement of the pump must be calibrated periodically. To this end, an automatic calibration-measuring system is provided consisting of a hollow sight glass having first and second sensors arranged in vertical relationship to each other adjacent to the sight glass such that, as a pump pumps the treatment liquid into the conduit, the upper level of the fluid will pass and be detected by each of the sensors. By correlating the distance moved by the upper level of the treatment liquid between the two sensors to the number of strokes of the pump, the volumetric displacement of the pump per stroke may be calculated to thereby calibrate the treatment system.
The above-described measurement system has proven to be effective for providing a continuous means of calibrating the system while continuing to provide flow of the treatment fluid to the conduit carrying the fluid to be treated. However, difficulties have been encountered in accurately determining the location of the upper level of the treatment liquid within the sight glass when the treatment liquid is a highly viscous fluid. When a viscous fluid is being calibrated, it tends to coat the sides of the sight glass and thus interfere with accurately determining the air/liquid interface at the upper surface of the treatment liquid.
Accordingly, there is a need for a mounting fixture for use in conjunction with a fluid measurement and pump calibration system wherein the mounting fixture is adapted to mount functionally different sensors to accommodate fluids having different characteristics. In addition, there is a need for such a mounting fixture in which the fixture may be used to mount either the upper or lower fluid sensor in the fluid measurement system.